How do I correct this? My desktop is upside down.

Maybe you have a "Southern Hemisphere Monitor". ;)

Actually, this is probably a setting in your video card.

Try pressing the Ctrl, Alt, and Up Arrow keys at the same time. For some systems, this may do the trick.

If that didn't work, then Right click the Desktop, select Properties->Settings->Advanced. Look for a tab that has your video card on it (something like nVidia, or Intel Graphics... ), click on that and then look for a setting to rotate the screen back to normal.

Good luck,
WallyH